Free The Attack of the Killer Rhododendrons by Glen Chilton

rhododendrons. Most field biologists come to be very fond of their study species. Not so Barron. He hates rhododendrons, and hates the grazing sheep that wander illegally into the national park from surrounding areas. Barron’s wife was also a biologist who had just finished a major report on rhododendrons in the region. Barron’s brother also has a job eliminating rhododendrons, demonstrating that eradicating introduced species can be a family affair.
    Barron explained that the rhododendron situation in Killarney National Park is not a simple one. It is clear that the original sites of infestation were Dinis Cottage and Muckross House, and that rhododendrons were first planted there about 150 years ago, probably for their ornamental value. At the time, some spots in the region had been cleared of their oak trees, and therefore had poor natural cover. Recognizing that rhododendrons grew very quickly, landowners had probably planted them for their shelter value. Today Muckross House has some monster rhododendrons with trunks the size of my torso, but these are a different species of rhododendron, not nearly so invasive. A big patch of
Rhododendron ponticum
in front of Muckross House, a potential source of seeds, had been eliminated some years earlier.
    At one time, Ireland was almost entirely blanketed by forests. Today, it is considered to be Europe’s least-wooded nation, and preservation of remaining oak forests is a very high priority. A management plan survey completed in 1990 showed that 75 percent of forest sites in the 11,000-hectare Killarney National Park were infested with the nasty type of rhododendron. Now, after twenty years of clearance efforts, major chunks of the park have been freed from its grip.
    In that period, three forms of control had been tried. The effortsof contract workers didn’t work as well as was hoped, possibly because of a lack of follow-up to make sure they had done the job properly. Attempts to control rhododendrons by park staff also didn’t work. For a spell, rhododendron duty was seen by park personnel as punishment for stepping out of line. More successful are the efforts of a non-profit group called Groundwork operating out of Dublin. Groundwork started off in 1981 as a small collection of Irish students with an environmental conscience. Willing to tackle an assortment of environmental challenges in Ireland, their chief mission is the elimination of rhododendrons from oak forests. Through three summer months, visitors from around the world sign on for one- or two-week work camps, dedicating themselves to rhododendron Armageddon. Volunteers stay in a hostel in Killarney National Park and travel each day to the site where their attentions are most needed.
    Because winds in the region generally blow from the west, and rhododendron seeds disperse long distances in the wind, clearance efforts proceed from west to east. The slopes of Torc are among the most heavily infested, but as the region was cleared of its oak trees many years ago, it is not the highest priority for rhododendron removal. In those regions where oak still stand, they continue to provide viable seeds, and an area can establish a new generation of oak even after forty years of rhododendron infestation. With luck, the seeds of other forest plants are still sitting dormant in the soil, waiting to germinate when conditions are right, or perhaps they will blow in from other forested regions. If so, the oak forest community may be able to re-establish its former glory and complexity.
    To get rid of rhododendrons, the first step is to cut them down or dig them up. Then you wait a year or so for the plants to try to grow back, and kill the new growth. The site needs to be revisited every few years to kill new rhododendron shoots. Many years must pass before an area can be declared free of the noxious plants. Barron explained that burning the chopped and uprooted rhododendrons would seem like an ideal end to them, but